An engine crankshaft converts reciprocating linear movement of a piston into rotational movement about a longitudinal axis to provide torque to propel a vehicle, such as but not limited to a train, a boat, a plane, a truck, or an automobile.
The crankshaft includes at least one crankpin that is offset from the longitudinal axis, to which a reciprocating piston is attached via a connecting rod. Force applied from the piston to the crankshaft through the offset connection therebetween generates torque in the crankshaft, which rotates the crankshaft about the longitudinal axis. The crankshaft further includes at least one main bearing journal disposed concentrically about the longitudinal axis. The crankshaft is secured to an engine block at the main bearing journal(s). A bearing is disposed about the main bearing journal, between the crankshaft and the engine block. Additional bearings are disposed between the crankshaft and connecting rods.
These bearings are subject to high loads and an environment that eventually tends to cause corrosion and erosion. Accordingly, materials are carefully selected to provide strength while at the same time resisting corrosion and erosion. However, the result is that the bearing is heavier than desired.